锑试金-同位素稀释-激光剥蚀电感耦合等离子体质谱法测定地球化学样品中痕量铂  

Determination of trace platinum in geochemical sample by isotope dilution-laser ablation inductively coupled plasma mass spectrometry with antimony fire assay

作　　者：王甜甜 毛香菊[1,2,3] 郭晓瑞 樊蕾 刘闫 倪文山 WANG Tiantian;MAO Xiangju;GUO Xiaorui;FAN Lei;LIU Yan;NI Wenshan(Zhengzhou Institute of Multipurpose Utilization of Mineral Resources,CAGS,Zhengzhou 450006,China;China National Engineering Research Center for Utilization of Industrial Minerals,Zhengzhou 450006,China;Key Laboratory for Polymetallic Ores'Evaluation and Utilization,Ministry of Natural Resources,Zhengzhou 450006,China)

机构地区：[1]中国地质科学院郑州矿产综合利用研究所,河南郑州450006 [2]国家非金属矿资源综合利用工程技术研究中心,河南郑州450006 [3]自然资源部多金属矿综合利用评价重点实验室,河南郑州450006

出　　处：《冶金分析》2024年第9期1-7,共7页Metallurgical Analysis

基　　金：国家自然科学基金项目(22106148);中国地质调查项目(DD20243355)。

摘　　要：Pt的测定多采用火试金富集后以电感耦合等离子体质谱法(ICP-MS)测定,试金扣通常需溶解后测定,不仅操作繁琐,而且存在溶液稀释效应。本文在样品中加入^(194)Pt同位素稀释剂,采用锑试金法对Pt进行分离富集,灰吹后得到锑合粒,将锑合粒打磨为表面光滑的锑片,采用激光剥蚀电感耦合等离子体质谱(LA-ICP-MS)测定同位素比值(^(195)Pt/^(194)Pt),按同位素稀释法公式对Pt进行定量,建立了火试金富集后固体直接进样测定地球化学样品中痕量Pt的分析方法。实验表明,采用自制提纯的Sb_(2)O_(3)作为捕集剂,并采用高纯石英坩埚代替传统火试金黏土坩埚,可使锑试金流程中的Pt空白值降低至0.52 ng,突破了火试金流程中Pt空白值过高的瓶颈;通过LA-ICP-MS面成像技术发现,锑片中^(194)Pt和^(195)Pt分布不均匀,但存在不均匀分布的趋势相似的规律;用LA-ICP-MS进一步多点剥蚀锑片中^(194)Pt和^(195)Pt,结果表明,6次测试^(194)Pt和^(195)Pt质谱强度的相对标准偏差(RSD)分别为14.7%和14.1%,但^(195)Pt与^(194)Pt质谱强度比值的相对标准偏差为2.5%,这说明同位素稀释剂中Pt与地球化学样品中Pt已充分交换。将本方法应用于地球化学标准物质中Pt的测试,测定值与认定值基本一致,测定结果的相对标准偏差(n=6)介于2.0%~5.1%之间。本方法实现了固-固联用分析新技术(固体高温熔融富集-激光剥蚀固体直接进样)和同位素稀释法对地球化学样品中Pt的测定。The content of platinum is usually determined by inductively coupled plasma mass spectrometry(ICP-MS)after enrichment by fire assay.The assay button should be dissolved for determination,so the operation is complicated and there is solution dilution effect.In this study,^(194)Pt isotope diluent was added into the sample,and platinum was separated and enriched by antimony fire assay.The antimony composite granule was obtained after cupellation and then polished to antimony slice with smooth surface.The isotope ratio(195Pt/^(194)Pt)was determined by laser ablation inductively coupled plasma mass spectrometry(LA-ICP-MS).The content of platinum was quantified according to the formula of isotope dilution method.Thus,a determination method of trace platinum in geochemical samples was established with direct solid sampling after fire assay enrichment.The experiments showed that when self-purified antimony oxide was used as collector agent and high purity quartz crucible was used instead of traditional fire assay clay crucible,the blank value of platinum in antimony fire assay process could be reduced to 0.52 ng,which broke the bottleneck of high blank value for platinum in fire assay process.LA-ICP-MS planar imaging results showed that the distribution of ^(194)Pt and 195Pt in antimony slice was not uniform,but the rules were similar for the trend of uneven distribution.LA-ICP-MS was used for the further multipoint ablation of ^(194)Pt and 195Pt in antimony slice.The results showed that the relative standard deviations(RSDs,n=6)of mass spectral intensity of ^(194)Pt and 195Pt were 14.7%and 14.1%,respectively.However,for the mass spectral intensity ratio of 195Pt and ^(194)Pt,the RSD was 2.5%,indicating that platinum in isotope diluent had been fully exchanged with that in geochemical samples.The proposed method was applied for determination of platinum in geochemical certifeid reference materials,and the results were basically consistent with the certified values.The RSDs(n=6)of determination results were between 2.0%an

关 键 词：锑试金 铂 同位素比值 高纯石英坩埚 同位素稀释法 激光剥蚀电感耦合等离子体质谱(LA-ICP-MS) 

分 类 号：O657.31[理学—分析化学] TF031[理学—化学]